Saint Helena is a small island in the South Atlantic Ocean which is part of the British overseas territory of Saint Helena, Ascension and Tristan da Cunha. The currency of the island is the Saint Helena pound, fixed at parity with the pound sterling. The island has authorised some private mints to issue coins under its jurisdiction, which come in a variety of sizes - including in the popular silver ounce (1 oz silver) format, usually denominated as £1.
This coin (denominated as 25 pence - like the early decimal crown coins) is part of The 2019 Empire Collection - Monarchs proof set issued by The East India Company, which features nine English monarchs, and is dedicated to King William IV of the United Kingdom (1765 - 1837).
William IV (William Henry) was King of the United Kingdom of Great Britain and Ireland and King of Hanover from 26 June 1830 until his death. The third son of George III and younger brother and successor to George IV, he was the last king and penultimate monarch of Britain's House of Hanover.
The Mint says about the set:
“Whosoever commands the sea, commands the trade, whosoever commands the trade of the world, commands the riches of the world and consequently the world itself.”
– Sir Walter Raleigh
From its very first voyage in January 1601, until it was dissolved and absorbed into the British Crown in 1874, The East India Company laid the foundation of the British Empire in the East. Overtime "The Company" rose to account for half of the world’s trade including cotton, silk, indigo dye, salt, saltpetre, tea and bullion. It had its own army and navy, its stocks were central to London’s financial markets and at one point it ruled over 400 million people. Learn the story of the world’s most famous Company through its coins. The 2019 Empire Collection is a series of nine silver proof coins which tell the story of a band of merchants who created an Empire through the monopoly, privilege and power bestowed on them by the Monarchs that ruled.
The East India Company continued to rule India with increasing centralisation of power. Parliament reforms and the Industrial Revolution created open markets and machine age goods. The British Empire stretched across most of the world. In an attempt to unify its territories, King William IV introduced a universal currency in India as a statement of power. Most significantly, the company lost its monopoly on Chinese trade, resulting in a “Tea Race” as ships from other companies competed to transport tea via some of the most important eastern trade routes.
The design of the coin features the portrait of William IV taken from his 1835 mohur coin, which was to become the highest denomination coin (gold or otherwise) among the East India Company’s coinage in India. | 
Search for Saint Helena: Silver Ounce 2019 Empire - William IV on eBay 
